A green solvent-to-polymer upgrading approach to water-soluble LCST poly(N-substituted lactamide acrylate)s

• Published in: Green Chemistry
• Main Authors: Pala, Marc, El Khannaji, Hafssa, Garay Sarmiento, Manuela, Carlos Ronda, Juan, Cádiz, Virginia, Galià, Marina, Percec, Virgil, Rodriguez Emmenegger, César, Lligadas, Gerard
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: Polimerització; Biocompatibilitat; Polymerization; Biocompatibility; DML
• Online Access: http://hdl.handle.net/2445/191183

We report a green solvent-to-polymer upgrading transformation of chemicals of the lactic acid portfolio into water-soluble lower critical solution temperature (LCST)-type acrylic polymers. Aqueous Cu(0)-mediated living radical polymerization (SET-LRP) was utilized for the rapid synthesis of N-substituted lactamide-type homo and random acrylic copolymers under mild conditions. A particularly unique aspect of this work is that the water-soluble monomers and the SET-LRP initiator used to produce the corresponding polymers were synthesized from biorenewable and non-toxic solvents, namely natural ethyl lactate and BASF's Agnique (R) AMD 3L (N,N-dimethyl lactamide, DML). The pre-disproportionation of Cu(I) Br in the presence of tris[2-(dimethylamino)ethyl]amine (Me6TREN) in water generated nascent Cu(0) and Cu(II) complexes that facilitated the fast polymerization of N-tetrahydrofurfuryl lactamide and N,N-dimethyl lactamide acrylate monomers (THFLA and DMLA, respectively) up to near-quantitative conversion with excellent control over molecular weight (5000 < M-n < 83 000) and dispersity (1.05 < D < 1.16). Interestingly, poly(THFLA) showed a degree of polymerization and concentration dependent LCST behavior, which can be fine-tuned (T-cp = 12-62 degrees C) through random copolymerization with the more hydrophilic DMLA monomer. Finally, covalent cross-linking of these polymers resulted in a new family of thermo-responsive hydrogels with excellent biocompatibility and tunable swelling and LCST transition. These illustrate the versatility of these neoteric green polymers in the preparation of smart and biocompatible soft materials.